Switching and/or controlling electric loads in a motor vehicle are conventionally performed with the use of simple switches (example: light on/off), pushbuttons (example: power windows or electrically adjustable side mirrors) or actuators (example: instrument lighting) in an electric circuit. The actuators are usually designed as analog devices. They are also designed specifically for a given process or load and they are arranged in a decentralized location. This also has the disadvantage that in the case of a plurality of electric loads, such as those in the case of modern vehicles, there must also be a plurality of power supply lines with plug connectors leading from the switches, pushbuttons and actuators to the individual loads.
In addition, there have also been attempts to use a computer to control some of the electric equipment of the motor vehicle. The computer is arranged centrally and is designed in part specifically for the control functions. It generates the control pulses for the electric component (the electric load). At the same time, the computer also performs certain “infotainment” functions, such as navigation, radio or telematics. One problem is optimizing the operating system to perform both infotainment as well as control functions. However, retrofitting and scalability of functions from the control area are problematical if hardware changes must be made in the PC.
German Published Patent Application No. 42 19 669 relates to a control unit for calculating control quantities for recurring control operations in a motor vehicle, including, in particular, engine management (ignition, injection) and the ABS brake system. The ignition module, the injection module and the brake module each include a microprocessor, a memory module and on/off circuits, and these modules continuously transmit the control quantities achieved over a connected databus to a central control unit. Any bus system suitable for data transmission in the motor vehicle may be used for this purpose.
European Published Patent Application No. 392,411 relates to an automotive controller having a central system manager module, which works together with load modules (air conditioner, power steering, transmission) over a bus. The system manager module, however, can be activated only when the user has identified himself correctly as the proper user. No special transmission protocol is provided.
German Published Patent Application No. 44 01 785 describes an integrated wiring system for a motor vehicle having a central control unit and a plurality of terminal control units that exchange data. This data exchange is not performed according to a standard protocol, but instead according to different communication protocols at different transmission rates.
European Published Patent Application No. 307,344 describes an automotive wiring system, in which user stations exchange data over a bus. Interface devices are connected to the user stations in a star network, with end devices (loads) connected in groups to the interface devices. There is no provision for combining them into load modules.
U.S. Pat. No. 5,732,074 describes a mobile portable wireless communication system, in which data transfer occurs between a remote computer and an automotive controller according to the Internet protocol. Data is converted in the motor vehicle and sent to a local control network, which operates according to another bus system (CAN), not according to the Internet protocol.